To drive a permanent magnet synchronous motor using a vector control, accurate rotor position information is required. In particular, an absolute position of the rotor may be detected using a resolver. However, an unbalance of a magnitude of a signal may occur due to a difference in a transformation ratio of the resolver, an unbalance exciting signal, a non-uniform inductance component, a distortion of a signal processing circuit, and the like, and thus error components may periodically occur in the position information. Therefore, motor control performance deteriorates and thus the motor is restrictively used in a high performance field.
As an existing method to reduce the position error in the resolver, a method has been developed for recording the error information previously measured by a precision position sensor in a memory such as a read only memory in a table form and compensating for the position error based thereon. Further, a method has been developed for modeling an output signal of a resolver using a regression equation and then estimating model parameters using a recursive least square method to minimize an error between a model value and a measurement value to compensate for the output signal of the resolver.
However, the methods for compensating for the position error of the resolver according to the related art are a method for measuring a position error when a speed is constant and have a limitation in compensating for the position error in the overall speed range.